The smoking route is an efficient means of drug delivery. Numerous drugs of abuse are administered by this route including cocaine, marijuana, phencyclidine, heroin and methamphetamine. Methods are under and pharmacodynamics of smoked drugs of abuse in human volunteer subjects. Healthy subjects with a recent history of abuse of the drug of interest by the smoking route will participate in the studies. Following informed consent, the subjects will smoke a low dose of the drug under controlled conditions to assess safety of the procedures. The subjects then will participate in a double blind, placebo controlled study of smoked versus intravenous administration of drug. Behavioral and physiological measures and biological samples will be collected over time. These data will provide important information to our understanding of the pharmacologic actions of these drugs by the smoking route.